Numerous devices are known in the prior art for controlling the vertical and horizontal passage of an article through a predetermined fluid environment. Such devices can generally by classified within one of two broad classifications; submarine and diving wing constructions for use in fluid environments, and flexible parachute constructions and rigid airfoil constructions used in gaseous environment. The present invention, while usable in devices in both classifications, is intended for use primarily in the later classification and particularly with inflatable glide parachute configurations using cellular construction and ram air principles.
Since prior to the advent of gliding parachutes, for many years, parachutes were constructed by sewing a plurality of panels together to define a hemispherical structure when inflated. Some of these domelike parachutes have incorporated slits, vents, or baffles for controlling the flow of air therethrough, both to facilitate deployment and to provide maneuverability. However, these parachutes are adapted primarily for nearly vertical descent, and generally do not prevent a load to be guided over substantial horizontal distances to a target landing area.
Recently, gliding parachutes have been developed for sport jumping, fire fighting, and military applications which can be readily manipulated to carry a load over a substantial horizontal distance. A typical gliding parachute is pre-formed and constructed in such a manner that when inflated it will define an airfoil in crossection. When a load is suspended from this type of inflated parachute, the parachute will glide forwardly and its airfoil shape will provide the necessary lift. By controlling the peripheral edges of the gliding parachute, the parachute and the load can be guided in their path of descent to a distant target. Numerous patents have been issued for ram air type gliding parachutes. U.S. Pat. No. 4,771,970 to Sutton, U.S. Pat. No. 4,729,530 to Jalbert, U.S. Pat. No. 4,705,238 to Gargano, and U.S. Pat. No. 5,537,207 to Germain, disclose recent examples of such ram air type parachutes.
Much emphases has been placed on the fabric and the rigging of configurations of previous gliding parachutes in an effort to approximate, as close as possible, a conventional airfoil shape. This results in maximum lift for a given parachute area which in turn provides maximum glide.
In a multi-cell gliding parachute, upper and lower fabric canopies are connected by laterally spaced fabric ribs. Suspension or support lines are connected at their upper ends to the parachute either directly or through flares, and converge downwardly to a harness or other load support structure. A plurality of control lines are connected at or near the trailing end of the parachute towards each side to permit control of steering and breaking. The fabric sections of the parachute are normally made of a high strength, lightweight fabric of suitable porosity.
One of the primary goals of inflatable multicell gliding parachutes using ram air type operation is to provide stability and maneuverability which are controllable both vertically and horizontally as the parachute travels through the atmosphere. it is desired to create a parachute which simultaneously minimizes bulk and weight and which is controllable through the vast array of maneuvers. However, while substantial steps have been taken towards this end in recent ends, further improvement is necessary and desired.
One manner in which the prior has addressed the provision of stability to such gliding parachutes is by providing "valves" within the multicell structure, which allow for the inflation of the air foil to a certain degree, with the valves tending to allow entry of air within the air foil, but discouraging the outward flow of air thereby. One such configuration is shown in U.S. Pat. No. 5,573,207 to Germain issued Nov. 12, 1996. In the configuration shown by example in Germain's FIG. 6, valve panels 39 are positioned within adjacent "cells" 34, with the inlet 37 of each cell 34 forming an air scope that serves as the opening into each cell through which the air flows to inflate the cells 34. In the embodiment shown there is at least one non-return valve 38 positioned within at least one, but preferably each, of the plurality of cells 34 that permits the flow of air into but resists the air flow out of each cell. In the configuration shown, each first valve may include a panel 39 of flexible material, which may suitable be zero permeability rip stock nylon of the like, having a bottom edge 40 positioned adjacent the bottom skin 14 and a top edge 42 position adjacent the top skin 12, with at least one of these edges being moveable.
Although the above-referenced configurations have their own advantages, they still have disadvantages. For example, the Germain reference has its free edges of its valve adjacent either the top or the bottom skins. This does not tend to stabilize the top leading edge of the canopy as does the invention described below. This is considered important by the applicant.
Therefore, it may be seen that a need exists for a canopy-type parachute which includes improved stability features, yet lends itself to relatively easy assembly. If valves are to be used, they should promote stability of the air foil by not allowing rapid deflation of the air foil, and their location and orientation should promote structural rigidity of the overall air foil, even out to the front top edge of the air foil. The valves used should preferably biased against a consistently taut surface, which provides a suitable base against which the valves can act and provide a valving action thereby.